Losing power around 4k xj650 max

I got this bike form my grandpa who passed away last year. I rebuilt the crabs replaced the spark plug and tested the Ohm on the coils. I did do a little adjustment to the clutch cable to make to more "snappier". I need to give it a lot of gas to get her out into first gear in first gear. the bike runs good up into 4k. I can hear the beautiful chirping noise until 4k then the engine note will change and will not want to accelerate until i shift until another gear. and the same pattern happens. is my cable to tight or am I not getting enough gas?? Sorry for any grammar mistake I made.

 

clutch cable should have 2 or 3 mm play at the clutch lever. sounds like it is starving for gas.main jet issue posibly. did you clean out the asperator tubes under the main jets?

bench sync the carbs? and of course running sync of the carbs?
3 or 4 k rpm is where the main jets start kicking in.
all the exhaust pipes getting hot?

 

The bike should not need a lot of gas at any time, unless it's to make it move really fast.
You need to revisit the carbs.

THE SECRET LIFE OF CARBURETORS

IN THE CHURCH OF CLEAN

Replacing your Hitachi throttle shaft seals

Setting the fuel levels

What are the idle mixture needles set to (turns out from a soft-seat)?


Unless...if the clutch is slipping....

Can you get it to immediately stall when letting the clutch out (at just above idle) while you're foot is on the rear brake?

 

cylinder 1 and 4 get really hot and cyinders 2 and 3 are just warm. I replace all the jets and asperator. I put new soilt screw and spring in but the do not turn all the way down.

 

ohm out your coil packs. sounds like you may have a problem with spark plugs or the spark plug cap or spark plug wires .just to rule them out as the issue.
then think about the carb 2 and 3.
ohm out the pickup colis too.

swap plugs from 2 and 3 to cylinders 1 and 4 see if the problem follows the plugs.

 

specs can be found in this thread
The Ultimate Relay, Switch, Sensor, and Diodes Guide

XJ650 models:

Pick-up coils:
1980-81 XJ650 Maxim and Midnight Maxim: 700 ohms +/- 20% = 560 ohms to 840 ohms acceptable range
1982 XJ650RJ Seca (non-yics engines): 700 ohms +/- 20% = 560 ohms to 840 ohms acceptable range
1982-84 XJ650 Maxim: 650 ohms +/- 20% = 520 ohms to 780 ohms acceptable range
1982 XJ650RJC Seca (yics engine): 650 ohms +/- 20% = 520 ohms to 780 ohms acceptable range
1982-83 XJ650 Turbo: 120 ohms +/- 20% = 96 ohms to 144 ohms acceptable range
Ignition Coils:
Primary side (input from main wiring harness):
2.5 ohms +/- 10% = 2.25 ohms - 2.75 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
11K ohms +/- 20% = 8,800 ohms - 13,200 ohms acceptable range
Spark plug caps:
5K +/- 20% = 4,000 to 6,000 ohms per cap acceptable range

Spark plugs:
0 ohms per plug

 

Spark plugs:
OK awesome thank you very much I will give this a shot and I'll let you guys know what I find.

 

just keep in mind you are checking ignition system to eliminate it as a problem. you may still have to dig back into those carbs

 

So I think I need to adjust the floats and all of the igitions system is up to spec besides the spark plug caps. I got new one on order.

 

Setting the fuel levels

 

Okay I revived the spark plug caps. No change yet. I am waiting to get my float measuring tool. I took her out she drove a ittle better. When I get up to about 5k and smash the thottle the bike doesn't move and I get a ot of poping back fire. I know this may be due to not the correct float hight.

 

So I have 2 coils that say 2 and 3. I put my left coil and #1 and #4 and and my right coil on #2 and #3 and she runs like a dream. I was drinkng down the road yelling wooooooo!!!!

 

Sorry not drinking drive